ESP32 Tutorial – Button Relay

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ESP32 Tutorial - Button Relay
Contents hide
1 Introduction
2 What is a Relay?
3 Hardware Components
4 Steps-by-Step Guide
5 (4) Uploading Code

Introduction

Controlling an appliance using a 5V SPDT relay module and an ESP32-WROOM microcontroller is a very common application used in everyday home automation and consumer electronics, allowing a foundational understanding of DIY home automation projects. In today’s tutorial, we are going to understand how to control any appliance wirelessly using an SPDT relay and an ESP32-WROOM microcontroller.

What is a Relay?

A SPDT relay is an electromechanical switch device that operates using a 5V DC voltage applied to its coil. It has one common terminal (COM) that can be connected to either a normally open (NO) or normally closed (NC) contact, depending on the relay’s state. When the 5V supply energizes the coil, it generates a magnetic field, causing the internal switch contacts to switch between these positions.

Hardware Components

You’ll need the following hardware components to get started:

ComponentsValue / ModelQty
ESP32–1
Push Button–1
Relay5v1
Power Adapter12v1
DC Power Jack–1
Breadboard–1
Jumper Wires–1
DC Power for ESP32–1

Steps-by-Step Guide

(1) Setting up Arduino IDE

Download Arduino IDE Software from its official site. Here is a step-by-step guide on “How to install Arduino IDE“.

(2) ESP32 in Arduino IDE

There’s an add-on that allows you to program the ESP32 using the Arduino IDE. Here is a step-by-step guide on “How to Install ESP32 on Arduino IDE“.

(3) Schematic

Make connections according to the circuit diagram given below.

ESP32-Button-Relay

Wiring / Connections

ESP32ButtonRelay
5V–VCC
GNDGNDGND
GIOP22Pin 3–
GIOP27–IN

(4) Uploading Code

Now copy the following code and upload it to Arduino IDE Software.

#define BUTTON_PIN 22  // ESP32 pin GIOP22 connected to button's pin
#define RELAY_PIN  27  // ESP32 pin GIOP27 connected to relay's pin

void setup() {
  Serial.begin(9600);                // initialize serial
  pinMode(BUTTON_PIN, INPUT_PULLUP); // set ESP32 pin to input pull-up mode
  pinMode(RELAY_PIN, OUTPUT);        // set ESP32 pin to output mode
}

void loop() {
  int buttonState = digitalRead(BUTTON_PIN); // read new state

  if (buttonState == LOW) {
    Serial.println("The button is being pressed");
    digitalWrite(RELAY_PIN, HIGH); // turn on
  }
  else if (buttonState == HIGH) {
    Serial.println("The button is unpressed");
    digitalWrite(RELAY_PIN, LOW);  // turn off
  }
}

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